noise induce hearing loss

7/18/2019 Noise Induce Hearing Loss

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Case study

National Journal of Otorhinolaryngology and Head & Neck Surgery, Vol. 2(11) No. 1, April 201434

Introduction

The harmful effects of noise on hearing have been knownth

since the middle of the 19 century & condition like1

“Boilermaker's deafness” are documented. In the early

times, noise was limited to working places like industry,

construction sites etc. Today the profile of noise sources is

changed with noisy activities, entertainments, music &

transportation. The noise from vehicles has increased

tremendously due to mushrooming number of various types

of vehicles plying on the roads. The production of such high

level of noise from these vehicles can have impact on hearing

of persons exposed. The persons most affected are traffic

policemen who work for long periods on roads and vendorswho work near noisy areas like railway platforms & shop-

2keepers . Traffic noise on existing urban road-ways lowers

the quality of life and property values for person residing in

vicinity of these urban corridors. Road traffic noise in big

cities is an important issue. Automobiles are important source

of noise pollution. It is high time to realize the importance of

protection against noise pollution on both local and global

bases. Surat is one of the fastest growing cities in India.

Population growth is also rapid & because of rapid

industrialization traffic is the major issue of the city. So we

planned this study of detecting hearing loss in persons

exposed to noise of heavy traffic areas of Surat city.

Aims & Objectives

1.To find the prevalence of hearing loss in people working in

heavy traffic areas of Surat. 2.To detect co-relation of hearing

loss with duration of exposure to noise. 3.To identify the

usefulness of screening for hearing loss in susceptible

population. Inclusion criteria: Those who are working /

residing at or around the selected traffic junctions for more

than 1 year and known to be exposed to traffic noise. i.e.

traffic police, vendors near traffic junctions, rickshaw drivers

etc.Exclusion criteria: If participant is known to have

exposure to accidental explosion, ear disease or undergone

any ear surgery. Those who gave negative consent for

inclusion in the study.

Methodology

This is the cross-sectional study conducted in Dept of ENT,

Govt Medical College, New Civil Hospital, Surat between

September 2011 to August 2013. We identified four heavy

traffic junctions in the Surat city having measured noise

intensity level of more than 65db. These were Udhna

Darwaja, Sahara Darwaja, Athwa Lines & Gujarat Gas Circle.Total 110 participants agreed and gave consent for inclusion

in the study. All the participants were called in batches of 5 to

10 to ENT-OPD, Govt Medical Collage & New Civil

Hospital, Surat. Detailed history was taken regarding number

of years of service/working at the selected traffic junctions.

Thorough ENT examination was done. Pure tone audiometry

was performed by Ishwarbhai Chaudhari (B.Sc. AST) of ENT

department. Data analysis was done on MS-Excel, and Epi-

info software.

Observations

There were total 110 participants included in the study. Not a

single participant at presentation had either complain of

decreased hearing or even a suspicion of it. Overall

prevalence of hearing loss was 68.2% (75 participants)

detected on pure tone audiometry. It was found that 56% (42)

had notch at 4 kHz in pure tone audiometry which was typical

of NIHL. There were 20% (15) with high frequency SNHL (4

kHz or more) and 21.3% (16) with mild SNHL. There was3

1.3% (1) each having moderate SNHL and profound SNHL .

Abstract

Surat is one of the fastest growing cities in India. Traffic-related noise pollution accounts for nearly two-thirds of total noise

pollution in an urban area. We selected four heavy traffic junctions in the Surat city having measured noise intensity level of more

than 65db. Total 110 participants agreed and gave consent for inclusion in the study. They underwent complete history taking,

ENT examination and audiological testing. Overall prevalence of hearing loss is 68.2%. 56% had notch at 4 kHz in PTA which is

typical of Noise Induced Hearing Loss. Maximum prevalence is seen in 55-64 yrs of age group which is 87.5%. Auto-drivers

have maximum prevalence of 77.8% followed by, 70.1% in traffic police and 46.6% in vendors. Athwa Lines, one of the selected

traffic junctions have maximum prevalence of 76.1%.

Key Words: Hearing loss, Prevalence, Traffic noise

1,4 2 3 5, 6Asst Prof, Resident, Prof & Head, Senior Resident, Dept of ENT-HNS, Govt Medical College,

New Civil Hospital, Surat.

Prevalence of hearing loss of people working in heavy traffic areas of Surat city1 2 3 4 5

Rahul B. Patel , Jalpa A. Patel , Jaymin A. Contractor , Anand V. Chaudhari , Dhaval C. Patel , Harshal6

M. Parmar - Surat ( Gujarat)




On assessing the hearing impairment according to “Degree of

hearing loss as per WHO guidelines” we found that 49.3%

had hearing impairment which includes 45.3% having slight

hearing impairment & 4% having moderate hearing

impairment. Rest 50.7% had no hearing impairment. We

found that 68.2% (75) participants had sensorineural hearing

loss (SNHL) and 31.8% (35) participants had normal hearing.

Maximum prevalence was seen in 55-64 yrs of age group

which is 87.5% followed by 77%, 63.6%, 57.6% & 50%

participants in age groups 45-54, 25-34, 35-44 & 15-24 yrs

respectively. These observations indicate that the two decades

from 45-64 yrs were more affected as compared to earlier two

decades 25-44 yrs of life. Out of 105 males, prevalence of

SNHL was 70.5% (74) and 29.5% (31) with normal hearing

while in 5 females 20% (1) had hearing loss and 80% (4) had

normal hearing. M: F ratio was 74:1. The prevalence of

hearing loss as per age in males, maximum prevalence of87.5% was detected in age group 55-64 yrs. This was

followed by 75%, 63.6%, 57.5%, and 50% in age groups 45-

54, 25-34, 35-44 and 15-24 yrs respectively. There was only

one female with hearing loss who belongs to age group 45-54

years. Among all participants, 77 (70 %) were traffic police,

15 (37.6%) vendors, and 18 (16.4%) are Auto-drivers. On

calculating the prevalence auto-driver has maximum

prevalence of 77.8% followed by, 70.1% in Traffic police and

46.6% in Vendors. It was observed that irrespective of the

occupation, 45-54yrs followed by 35-44yrs are the two most

commonly affected age groups or decades in all three

occupations. The prevalence of HL for these two age groups

was 48.1% & 25.9%, 57.1% & 14.3% and 50% & 28.6% in

traffic police, vendors and auto drivers respectively. Extremes

of the age groups i.e. 15-24 and 55-64 were the least

commonly affected age groups in all three occupations. On

analyzing the age-wise prevalence in different occupations, it

was observed that higher prevalence was seen in traffic police

in all age groups as compared to vendors and auto-drivers. In

this study four heavy traffic junctions were selected: Udhana

Darwaja, Athwa Lines, Gujarat Gas Circle & Sahara Darwaja.

Maximum 44% (33) participants were from Gujarat Gas

Circle. This was followed by 38.7% (29) from Sahara

Darwaja, 36% (27) from Udhana Darwaja and 28% (21) from

Athwa Lines. On calculating area vise prevalence of hearing

loss it was found that Athwa Lines had maximum prevalence

of 76.1% followed by 69.7%, 66.7% and 62.1% at Gujarat-

gas circle , Udhana Darwaja and Shara Darwaja respectively.

On calculating area wise prevalence in different occupations,

traffic police had highest prevalence at all traffic junctions

which was 66.7% at Athwa Lines It was followed by 32.1%,

44.4% and 30.3% at Sahara Darwaja and Gujarat Gas Circle

respectively. In auto drivers prevalence was 28.6% at Gujarat

Gas Circle, 22.2% at Udhna Darwaja and 9.5% at Athwa

Lines. Enrolled vendors were all from Gujarat Gas Circle and

prevalence of HL was 28.6%. On calculating the Prevalence

of hearing loss according to duration of noise exposure, it was

found that in participants with less than 2 yrs of exposure

prevalence was 68% (17). Prevalence of hearing loss was

67.6% (23) in participants who exposed to noise for 2-4 yrs.

There were 72.7% (16) for 4-6 yrs, 87.5% (7) for 6-8 yrs, 75%

(6) for 8-10 yrs and 46.2% (6) for more than 10 yrs. Mean

years of noise exposure was 5.36 yrs. We found that

irrespective of the duration of exposure 45-54 yrs followed by

35-44 yrs age groups were the most commonly affected age

groups. It was observed that prevalence of hearing loss was

67.2% (45) in participants having exposure of noise for <5 yrs

and prevalence of hearing loss was 69.8% (30) in participants

who exposed to noise for 5 yrs or more. It was statistically notsignificant. It was observed that prevalence of hearing loss

was 68% (17) in participants having exposure of noise for <2

yrs and prevalence of hearing loss was 68.2% (58) in

participants who exposed to noise for 2 yrs or more. It was

statistically not significant. Amongst the participants <42 yrs

of age we found that prevalence was 36.7% in those having >5

yrs of noise exposure while it was 28.9% in those having <5

yrs of exposure. The participants having age 42 yrs or more,

prevalence of hearing loss was 71.1% in those having <5 yrs

of noise exposure and 63.3% in those having noise exposure

for >5 yrs or more. Amongst the participants <42 yrs of age

we found that prevalence was 34.5% in those having >2 yrs of

noise exposure while it was 23.5% in those having <2 yrs of

exposure. The participants having age 42 yrs or more,

prevalence of hearing loss was 76.5% in those having <2 yrs

of noise exposure and 65.5% in those having noise exposure

for 2 yrs or more . There were 14.7% (11) participants with

unilateral hearing loss & rest 85.3% (64) participants with

binaural hearing loss.

Discussion

This is a cross-sectional study conducted between September

2011 and August 2013. Four heavy traffic junctions in Surat

city were selected and the study included Traffic Police, Auto

drivers and Vendors who were working in a noisy

environment for more than 1 year. Total 110 participants were

included in the study. Overall 68.2% prevalence of

Sensorineural hearing loss (SNHL) is observed in the study

population. A very interesting fact observed in our study is

that not a single participant among this high risk group has

complained or suspected [themselves or by their family]

hearing loss. This indicates the insidious nature of the HL and

the utmost importance of counseling & regular follow-up of

35




this group for early detection, treatment and/or rehabilitation

for hearing loss. As against the overall prevalence of 68.2%,

we found that male has prevalence of 70.5% and female has

20%. This is comparable to Study done by Shrestha I et al on

traffic police, showed that there was 66.4% prevalence of3

noise induced hearing loss. A study done by R Deepak on

Traffic police showed that 21% prevalence of noise induced2

hearing loss and 18% of high frequency SNHL . In this study

regarding configuration of audiometric curve it is found that

56% participants had notch at 4 kHz in pure tone audiometry

which is typical of NIHL. There are 20% participants with

high frequency SNHL (4 kHz or more) and 21.3% participants

had mild SNHL. One candidate each had moderate SNHL and

profound SNHL comprising 1.3% in each category. A study

done by Shrestha I et al showed that 66.4% had a clear notch at1

4 KHz. There is another study done by R Deepak who

concluded that 21% had noise induced hearing loss with notch2at 4 KHz . In this study as per WHO definition and grading of

hearing impairment total 49.3% participants had hearing

impairment; out of them 45.3% have slight hearing

impairment and 4% have moderate hearing impairment. A

study done by R Deepak showed that 51.8% had mild hearing2

loss, 13.6% had moderate & 0.9% had severe hearing loss. A

study done by Shrestha et al showed that 81.2% had SNHL

which was of moderate to severe intensity in 37.7% of4

individual . Maximum prevalence of hearing loss found to be

in 55-64 yrs of age groups which is 87.5%. This is followed by

77%, 63.6%, 57.6% & 50% in age groups 45-54, 25-34, 35-44

& 15-24 yrs respectively. This indicates, later two decades

(i.e. 45-64 yrs) are more affected as compared to earlier two

decades (25-44 yrs). A study done by V K Singh et al showed

that there is equal distribution of hearing impaired individuals5

in all age groups . In this study 95.4% participants were males,

while 4.6% were females. Lesser number of females in the

study is due to obvious reason that in Surat city majority of

Traffic police & all Auto drivers are male. All the females

included in the study are vendors. Out of 75 participants,

98.7% are males and 1.3 % is females thus M: F ratio is 74:1.

On calculating the age-wise prevalence in males, maximum

prevalence of 87.5% is found in age group 55-64 yrs followed

by 75% in age group 45-54 yrs. In a study done by Shrestha et

al mean age was 29 years and 74.5% were males & 25.5%4

were females . In this study auto-drivers have maximum

prevalence of 77.8% followed by, 70.1% in traffic police and

46.6% in vendors. It was observed that irrespective of the

occupation the age group 45-54 & 35-44 yrs are most

commonly affected. Prevalence is 48.1% & 25.9%, 57.1% &

14.3% and 50% & 28.6% respectively in traffic police,

vendors and auto drivers. Extreme of the age groups i.e. 15-24

and 55-64 are the least commonly affected age groups in all

three occupations. A study done by V K Singh et al showed

that hearing loss increases when duration of exposure to noise5

is increases . There are 14.7% participants with unilateral

hearing loss & rest 85.3% with bilateral hearing loss. A study

done by Shrestha I et al showed that 40.9% had bilateral4hearing loss and 25.7% had unilateral hearing loss.

Conclusion

The Diamond city Surat ranks fourth in a global study of the

fastest developing cities conducted by The City Mayors

Foundation, an international think tank on urban affairs.

However this growth comes at a price. Noise pollution and

consequent hearing loss is part of the price paid by urbanites.

This study documents a very high prevalence of 68% of HL.

This is very alarming and more so because this is insidious and

unsuspected. As expected, those in the higher age groups and

greater number of years of exposure show higher prevalence

of hearing loss. Traffic policemen are uniquely susceptible as

they have to be continuously exposed to noise for 8 hrs/day in

their duty. Measures that can be implemented to reduce

prevalence of hearing loss include; Mass transportation,

Distribution of traffic by sensible road & traffic signal

planning, Restricting number of duty hrs to 4-6, Banning

noisy and illegal horns and sirens, Making susceptible people

aware about hearing impairment and encouraging regular

ENT examination, Transfer of those with hearing loss to less

noisy area or having compulsory rotation in duty,

Encouraging use of noise-reduction devices or ear protectionwherever possible.

References

1. Alberti PW, Scott-Brown's Otolaryngology-Adult

Audiology, 1987; 5(2): 595.

2. Deepak R, “Assessment of traffic noise & its impact on

certain personnel”, Indian Journal of Otolaryngology &

Head and Neck Surgery, 1997; issue 1(49): 47-50.

3. Anirban Biswas, Clinical Audio-vestibulometry for

Otologist & Neurologist.1995 (2): 12

4. Shrestha I, Shrestha BL, Pokharel M, et al, “Prevalence

of noise indused hearing loss among traffic police personnel of Kathmandu metropolitan city”, ENT-HNS

Kathmandu University Medical Journal, 2011;36(4):

274-8.

5. V.K.Singh “Prevalence of occupational noise induced

hearing loss amongst traffic police personnel” Indian

Journal of Otolaryngology & Head and Neck Surgery,

Apr-June 1999; 51(2):23-26.

Address for correspondence

Dr. Rahul Patel

Assistant Professor, Govt. Medical college, Surat

Cell : +91 9099947181 E-mail [email protected]

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noise induce hearing loss

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